This invention relates to a tape cassette, and more particularly, to a continuous loop tape cassette having a separate tape guide for guiding tape along the open front of the tape cassette and across a magnetic head of an external tape player/recorder apparatus.
Shown in FIG. 1 and described more fully hereafter is a conventional continuous loop tape cassette presently in use which is designed to store and dispense magnetic recording tape continuously. More particularly, between a cassette base and cover, a single tape hub carries a tightly wound continuous coil of tape. The tape exits the middle of the coil and passes over a "tape guide region," while being exposed to the magnetic head of an external tape player/recorder apparatus. The tape then passes along a resilient pinch wheel, which urges the tape against a drive capstan of the external apparatus, and returns to the outside of the tape coil. This tape travelling path is repeated throughout operation of the cassette.
Another example of the above-described type of continuous loop tape cassette is described in U.S. Pat. No. 4,013,239, issued to Beswick et al.
To ensure optimum operation of a continuous loop tape cassette, it is important that the tape crossing the magnetic head be properly oriented to ensure proper contact between the running tape and the magnetic head. Improper operation is often the result of improper orientation of the tape at the tape guide region. Thus, the tape guide region of a continuous loop tape cassette must be molded according to strict structural parameters.
This need to manufacture according to strict structural parameters must be balanced against the need of economy of construction because of the vast quantities of compact, continuous loop tape cassettes made and sold.
Until now, this balance has best been met by molding most of the tape guide region integrally of the cassette base. More particularly, conventional continuous loop tape cassettes usually include a tape guide region having two "conical posts" molded in the front open area of the cassette base, as shown in FIG. 1. It is also known that to promote proper tape orientation, each conical post must then be separately capped by a metal washer which overhangs the post to form a "shelf". As the tape travels around the conical posts, the tape is caused to ride up the slightly slanted surfaces thereof until the upper edge of the tape abuts the shelf. Thereafter, the tape is guided by the conical posts and the shelf.
This conventional arrangement has the following general disadvantages.
Firstly, the structural accuracy of the tape guide region is only as good as the molding process used to form the conical posts integrally of the cassette base. Molding plastics to certain structural specifications can be very difficult and expensive. The more detailed the structural specifications of the molded product, the greater the chance for mold imperfections, especially where cost of manufacturing is a preoccupation. More particularly, the conical posts are difficult to mold accurately onto the cassette base because of the posts' internal location on the cassette base. In addition, it is known that the shelf must necessarily be a separate piece from each conical post because it is almost impossible to accurately mold the posts and shelf integrally of the cassette base.
Secondly, the metal washers making up the separate shelf are difficult to apply to the tops of the posts by automation. Accordingly, efficient automation, a goal of any manufacturing process, is difficult to effect with the prior art design. In addition, if clearance exists between the mounted washer and the cassette cover, the washer may undesirably move during operation of the cassette and change the orientation of the tape.
Thirdly, since the tape guide region must be made of a plastic having a low coefficient of friction which is usually relatively more expensive, the cassette base molded integrally therewith must also be molded of the same relatively expensive plastic.
From the foregoing, it can be seen that an improved tape guide region for a continuous loop tape cassette is desired which effectuates proper orientation of the tape in the tape cassette crossing the magnetic head of a tape player/recorder and which is relatively simple in structure such that it may be manufactured and assembled easily, accurately and costefficiently through automation.